Quantitative spectrometric analyses of the contents of flavonoids, tannins and total polyphenols in the aerial parts of rock samphire--Crithmum maritimum L., collected from three separated geographic locations along the Adriatic coast of Croatia in different growth stages, are reported. The results point to variability of the analyte content as a function of the growing site and growth stage. The content of flavonoids was found to be 0.08-0.42%. The highest content of flavonoids was found in the samples collected before flowering. The content of tannins ranged from 0.10 to 2.65%, while the content of total polyphenols varied from 4.72 to 9.48%. The highest contents of tannins and total polyphenols were found in the samples collected before flowering and at the beginning of flowering.